WCTT analysis of avionics Switched Ethernet Network with WRR Scheduling

Abstract

Nowadays, a real-time embedded system often has to cope with flows with different criticality levels. Such a situation is forecasted for next generation avionics networks, in order to better use communication resources. Indeed, the present situation, where the Avionics Full Duplex switched Ethernet (AFDX) network is reserved for critical avionics flows, leads to a very lightly loaded network.Quality of Service (QoS) mechanisms such as service disciplines are mandatory in order to cope with the heterogeneous constraints of the different kinds of flows. Weighted Round Robin (WRR) is envisioned in the context of avionics.Worst-case traversal time (WCTT) analysis is mandatory to ensure that temporal constraints of flows are met. Network Calculus (NC) is a popular solution for this analysis and results exist for WRR. They lead to pessimistic upper bounds.The main contribution of this paper is to show how existing NC results for WRR can be applied and improved in the context of an avionics configuration. The resulting analysis is evaluated on an industrial size configuration.

A Survey on Network Calculus Tools for Network Infrastructure in Real-Time Systems

“…Argibay-Losada et al [62] propose a ring network with ten switches, which is used to manage vehicular traffic in a metropolitan area, in 5G scenarios. Soni et al [63] evaluate an industrial-size network with eight switches. Hotescu et al [64] conduct research on an AFDX network with seven switches.…”

Optimizing Network Calculus for Switched Ethernet Network with Deficit Round Robin

“…where F h Cx is the set of C x flows crossing port h. As an example, let us consider the output port S 1 4 in Figure 2. 5 flows of class C 1 are scheduled by FIFO, leading to F 5 . The overall arrival curve of class C 1 can be computed by:…”

“…In this section, we compare our optimized WCTT analysis for DRR with the WCTT analysis for WRR presented in [5]. The WRR analysis cannot cope with the realistic case study presented in previous sections.…”

“…A different case study is considered in [5]. It has a similar network architecture as well as a similar number of flows.…”

“…Deficit Round Robin (DRR) and Weighted Round Robin (WRR) are such mechanisms and they are envisioned for future avionics networks. We have proposed a first evaluation of WRR in the context of avionics in [5]. In this paper we focus on DRR.…”